The yieldable structure is situated between the rigid rim of the steering wheel and the steering column, and enables the steering wheel, on impact, to rotate with respect to the steering column so that it becomes disposed parallel to the surface of impact of the driver.
In this manner, the force of impact is discharged over a relatively large surface, so minimizing the specific pressure on the driver's body.
However, these devices do not completely eliminate the potential danger represented by the steering column. In fact, very violent impacts could cause piercing of the yieldable structure, so that the steering column and driver's body are brought into violent contact.